Strain gauge transducers have been used for many years to measure bending moment applied to a beam secured at one or both of its ends to an object to which a force is being applied as a means of monitoring the force and other derivable parameters of interest. It has heretofore been common practice to mount strain gauges on one and more preferably on opposite sides of the beam in the same location adjacent the point at which the beam is secured to the object and then electrically connect the gauges in the same or on opposite legs of a wheatstone bridge suitably adapted to provide an output signal indicative of the effect of tension or compression upon the gauges caused by bending the beam which in turn can be used to determine bending moment due as a function of their respective locations which in turn can be used to determine the force being applied to the object and other parameters derivable therefrom by methods well known to those skilled in the art of beam bending moment analysis.
One of the problems up to the time of present invention associated with such prior-art transducer type measuring devices has been that heretofore the force has been applied generally in a direction transverse to the neutral axis of the bending member which results in a different bending moment at any given location along the beams for beams having one end secured to the object and which also may be different for identical symmetrical locations from the point of securement from beams that are secured at both ends when the force is not applied transversely at the midpoint location between oppositely secured ends.
In addition to the change in bending moment along the length of beams heretofor utilizing strain gauge transducers for providing desired information, the bending moment generally varies over infinitesimal distances along the length of the beam resulting in a gradient of bending moment even over the breadth of the strain gauge transducer resulting in uneven tension or compression imposed thereupon by the bending beams.
The varying bending moment phenomenon hereinbefore described results in great criticality in locating the strain gauge transducers along the beam for it is desirable to locate them at a point where the bending tension and compression is a maximum so as to provide the highest output signal possible. Consequently, singly or doubly supported beams which bend upon application of an applied load transverse to their longitudinal axis result in an almost infinite number of differing bending moments along their length which reduces effectiveness, accuracy, and consistency of strain gauge transducer measurements as well as imparting a bending moment gradient across the strain gauge transducer that even further accentuates the complexity and inaccuracies involved.